We found this circuit in a 1964 Electronic Design. It provides 0.5 V signals from 4 kHz subcarriers. Transistors are from the era.
This circuit was obtained in the 1977 RCA CMOS manual. The circuit has the frequencies determined by the...
We found this circuit in a 2004 documentation. The circuit consists of a standard lamp for testing...
Found in a Popular Electronics of the 90s this configuration can be seen elsewhere on our site....